The present invention, refers to an apparatus for temporarily holding logs within cutting-off machines.
In the following text, the term “logs” is meant to indicate rolls of web material (such as paper) wound up around a support core (for example, a tubular cardboard core), to be cut to form rolls of smaller length, that is, of commercial size.
At present, the production of paper rolls is known to involve cutting transversally the logs, produced by a rewinding machine, by using one or more cutting-off machines.
A cutting-off machine for logs is described in details in the patent IT-1247330.
Essentially, a cutting-off machine of this type comprises:                a plurality of channels or guides into which the logs are discharged and in correspondence of which movable devices, so-called “porters” in jargon, are mounted to drive the logs into longitudinal motion by pushing them from behind;        a cutting station, comprising one or more circular blades, rotating about axes parallel to those of the logs and fixed on a corresponding movable support;        means for temporarily holding the logs in said cutting station.        
During the normal operation, a log to be cut is disposed, by a relevant porter, in a preset position on the respective guide and blocked in such position; then, one of the blades is actuated, that is, it is driven into a plane orthogonal to the axis of the log, so as to form a shorter roll of preset size therefrom. The length of the roll depends, actually, on the advancement of the porter during the time elapsing between two consecutive cuts operated by the blades.
In particular, the means currently used to hold temporarily the logs in the cutting station, means which are commonly called “pressers”, comprise a plurality of belts associated with corresponding driving members by which the configuration of said pressers can be modified in order to hold the logs during the cutting steps and release them when they have to be moved.
However, the traditional pressers result inadequate to the current production requirements, both in terms of reliability in the long run, especially as far as the operation flexibility is concerned, and of service demands.
The main object of the present invention is to overcome the said drawbacks.
This result has been achieved, according to the invention, by adopting the idea of making a structure having the characteristics described in claim 1. Further characteristics being set forth in the dependent claims.